The invention pertains to ambient condition detectors. More particularly, the invention pertains to such detectors which incorporate maintenance enhancing circuitry.
Known monitoring systems can be installed in and used to monitor a variety of conditions in a region such as some or all of a building. Such systems, for example, fire alarm or burglar alarm systems, provide on-going indications as to the presence of certain pre-defined conditions. Representative conditions include the presence of fire, such as perhaps indicated by the presence of heat or smoke, or the presence of intruders into a region such as might be indicated by infrared radiation emitted from persons or animals in a region being monitored.
Known systems usually include a plurality of ambient condition detectors which are often dispersed throughout the region. It is also known that such detectors from time to time may need replacement or maintenance. Known types of maintenance include repair or replacement of components in a respective detector or cleaning same.
Detectors may communicate wirelessly or by a wired medium such as an optical or an electrical cable. In wired systems, the detectors can be hardwired to the medium. In such instances, depending on the design of the system, it may not be possible to continue normal system operation with respect to remaining detectors when one of the detectors is disconnected for maintenance or replacement purposes. There is also the inconvenience and time involved in having to disconnect/reconnect the detectors.
Additionally, even if it might be possible to carry out the maintenance work while the respective detector is connected into the system, with the system remaining operational, such activities may increase the likelihood of false alarms which are undesirable.
It is also known in some systems to provide detectors which removably engage respective bases. The respective base or bases can be coupled to one another or to displaced control elements via respective cables. In such installations, a detector which has been removed for maintenance can be temporarily replaced by another unit if desired. Often such systems include circuitry or executable instructions which enable the respective system to continue with substantially normal operation even if the location of a detector which has been removed for maintenance is not temporarily filled with a substitute.
Adverse consequences may result even in systems which incorporate detectors which are removably coupled. For example, where the systems include one or more computers or programmed processors which are executing instructions, the software might receive erroneous signals or messages due to the temporary removal of one or more detectors. Potential problems might include causing software to inappropriately reset with a loss of previously stored data, communications or timing. Thus, even where the detectors are intended to be removably coupled to a system, there are benefits in not having to remove them to carry out routine maintenance.
There continues to be a need for devices which can be temporarily disabled, without physically having to remove the device from the system, for purposes of routine maintenance. Preferably, the existence of such structures would be substantially transparent to other detectors or system control elements. Additionally, it would be preferably if such structures could be incorporated into detectors without substantially increasing either the cost or the manufacturing complexity thereof. Finally, it would be preferable if such structures did not adversely affect the external aesthetic appearance of the respective detectors.
Structures and methods in accordance with the present invention contribute to being able to perform maintenance on electrical devices which are part of a multi-device communication system without disabling or causing a loss of power to any portion of the respective system to which a respective device receiving maintenance is interconnected. Additionally, the respective device continues to receive power and can carry out maintenance related functions, if desired, during the maintenance procedure.
In a preferred embodiment, a switch element which has at least two states is incorporated into the electrical device. The state of this switch can be manually or automatically changed at the beginning of a maintenance procedure.
The change of state provides a signal to the respective device that it has gone from a normal operational mode to a maintenance mode. In a maintenance mode, the respective device will not necessarily emit the same output signals as in a normal operational mode. The maintenance mode output signals can not only be used to inform other devices in the system that the respective device is undergoing maintenance but also the likelihood that false or inappropriate signals or messages will be emitted from a device undergoing maintenance is substantially reduced.
In yet another aspect, a monitoring system includes a plurality of ambient condition detectors. At least some of the detectors include control circuitry having a normal operational mode and a maintenance mode. The respective detector or detectors can be placed into the maintenance mode by actions taken locally in the vicinity or at the detector.
In a preferred embodiment, a switch is used to indicate that maintenance is being performed on a device. This switch may be manually activated or automatically activated during the maintenance procedure.
One method of automatically operating the switch is to detect the removal of a cover or another part that is normally removed or moved in position during the maintenance procedure. Other structures for detecting the changing in position of parts of the device during a maintenance procedure are also within the spirit and scope of the present invention.
Switches of various types, mechanical, magnetic, proximity, or optical, can be used to detect the maintenance processes. A mechanical switch could include metal contacts or carbon rubber or other conductive medium that shorts out points on a printed circuit board. Other types of switches can also be used, including multi-state (more than two state) switches. An example of another approach could be by monitoring the position of a part optically and noting a change in the optical signal. The switch could be manually activated or automatically activated.
The switch is placed into a maintenance state, at the start of the maintenance process, to disable the device from exhibiting alarm or other environmental indications. The switch is returned to its normal state after servicing.
In one embodiment, a change of state of a switch in the device can result in a message transmission to some external device. That external device, such as a system control unit, could then send a message back to the respective device (containing the switch whose position was changed) to not send alarm indications. This method includes the control unit or other external device in the process of disabling alarm indications when the device is placed into a maintenance mode.
In another embodiment, a change of state of a switch in a device can result in a message transmission to some external device. That external device, such as a system control unit, could then ignore alarm transmissions or indications from the respective device. When the switch is changed back to its normal position, the device can transmit a message indicating that it has returned to a normal operational state. The external device would then no longer ignore alarm transmissions or indications.
A time delay can be used with the switch function. This delay will permit an alarm indication to be transmitted after a predetermined period of time during which the maintenance is to be performed. This time delay is not necessary if the system can recognize that the maintenance is taking place and appropriate indications are given. However, if the system cannot recognize that the device has been disabled from giving an environmental condition indication, then a fail safe can be provided. In this instance, the switch function is automatically returned to normal after a predetermined period of time regardless of whether the service has been completed.
In a preferred approach, the switch would be incorporated into the device and automatically change state when the cover or some other part is removed or changed in position during maintenance. Automatic operation of the switch would make it easier for the person performing the maintenance. In addition, automatic operation will minimize the likelihood of service personnel creating false alarms by failing to place the device in the maintenance mode prior to servicing it.
Products that are hardwired and not easily removable benefit from this invention. Duct detectors, power devices, and hardwired sensors are examples. In the case of the duct detector, when the cover is removed for maintenance, the circuitry is disabled from indicating an alarm condition.
In an alternate application, the device itself could monitor what maintenance was performed, store this information, and possibly report it to an external device. The reporting could be automatically activated or activated by request messages or other request indicators. The external device could be a control unit connected to the communications link, a portable device that accesses the information, or a modem link to a remote location.
A device with the cover removed could provide an audible or visual (or both) indication that the monitoring function (i.e. smoke) has been disabled (as long as the cover is not in place). A rapidly pulsing light emitting diode could be a visual indication of the device being disabled from detecting environmental conditions. A color change (i.e. yellow) could indicate this same condition. A xe2x80x9cchirpingxe2x80x9d horn could indicate that the device is disabled from detecting environmental conditions. Many different methods of indication can be used including digital/analog displays.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings.